' MCP23017.bas I2C test

 const mcp23017 = &h20 ' A2, A1, A0, R/W all connected to 0V
 Const i2caddr=mcp23017
 const IODIRA = &h00 ' Port A IO Direction register DEFAULT = I/P
 const IODIRB = &h01 ' Port B IO Direction register DEFAULT = I/P
 const IOCON = &h0A ' IO Expander config register - address &h0B accesses  same register
 const GPIOA = &h12 ' Port A General purpose register
 const GPIOB = &h13 ' Port B General Purpose register
 const OLATA = &h14 ' Port A latch register
 const OLATB = &h15 ' Port B latch register
 const GPUPA = &h0C ' Port C pull-up register
 const GPUPB = &h0D ' Port B pull-up register

' SetPin 14,I2C0sda
' SetPin 15,I2C0scl
 SetPin 1,I2C0sda
 SetPin 2,I2C0scl

 I2C open 100, 1000
 I2C WRITE MCP23017,0,2,IODIRA,0 ' set direction to output
 I2C WRITE MCP23017,0,2,IODIRB,0 ' set direction to output
'  I2C WRITE MCP23017,0,2,GPUPB,&h3f ' set weak pullups on all except bits 6&7

do
 mcp17
loop

sub mcp17
'  I2C WRITE MCP23017,0,2,IODIRA,0 ' set direction to output
'  I2C WRITE MCP23017,0,2,IODIRB,0 ' set direction to output
 print "write to mcp23017 at ";MCP23017
 for i = 1 to 6
   I2C Write MCP23017,0,2,OLATA,&b10101010 '  
   I2C Write MCP23017,0,2,OLATB,&b01010101 '  
   PAUSE     1000
   I2C Write MCP23017,0,2,OLATA,&b01010101 '  
   I2C Write MCP23017,0,2,OLATB,&b10101010 '  
   PAUSE     1000
 Next i
 I2C Write MCP23017,0,2,OLATA,0 ' turn all off
 I2C Write MCP23017,0,2,OLATB,0 ' turn all off
 pause 1000
end sub